Obsession over triple channel memory

[weaverra]

Why the obsession? I just recently installed 16GB (4x4GB) in my 2009 MP and it's fantastic. I haven't paged or compressed one time since I installed it. I've been using LR and PS simultaneously. If I had a triple channel configuration of 12GB (3X4GB) I would have most certainly paged out and compressed by now. I haven't seen over 12GB of usage so far. Currently sitting at 12.81GB of usage right now. Even if I had a super fast SSD I still want to prevent paging to reduce writes to the drive. I don't see any benefit what so ever. Am I missing something?

 

[Peteman100]

Number of channels is about bandwidth, not amount of total memory. Three channels provides 50% more bandwidth than two.

 

[DanielCoffey]

I was under the impression that in the real world the difference was marginal (a few percent) and that, except for a few specialist applications, more memory in dual channel was better than less in triple channel... provided you actually used the extra of course.

 

[Umbongo]

Why the obsession? Am I missing something?

Just a misunderstanding over the impact to performance that memory bandwidth has in a workstation for most people. Three has to be better than two right? Well it is, but not to where it matters. 2, 3 or 4 DIMMs is all fine. 4 is better than two, the performance of how the interleaving works with 4 DIMMs actually gives more bandwidth than just having two.

 

[Gav Mack]

It's the same obsession that has been with dual channel PC setups for over 15 years (the Rambus/DDR SDRAM wars). When you use all your available ram up you can notice the difference particularly with DDR3; far more than say smaller increases in the past like with DDR2 with smaller gaps such as 533,667,800. It's not much, probably 5 %. But marginal gains I do like. These Xeons come with a triple config - other CPU designs have a quad option.

My 4,1 came with 3x1Gb which is useless - so along with the hex Xeon I bought 3x8gb DDR 1333. Which means if I go dual socket I will have the same memory config for both processors for 48Gb.

 

[AidenShaw]

I was under the impression that in the real world the difference was marginal (a few percent) and that, except for a few specialist applications, more memory in dual channel was better than less in triple channel... provided you actually used the extra of course.

Just a misunderstanding over the impact to performance that memory bandwidth has in a workstation for most people. Three has to be better than two right? Well it is, but not to where it matters. 2, 3 or 4 DIMMs is all fine. 4 is better than two, the performance of how the interleaving works with 4 DIMMs actually gives more bandwidth than just having two.

Marginal is correct. There was a thread discussing performance of the MP6,1 with 1,2,3 and 4 DIMMs (nMP & memory performance observations with various mem configs) Bottom line - almost all of the benchmarks performed the same with different configs. Only two (one of them a memory bandwidth benchmark) were sensitive to the number of DIMMs.

Plus, if you need the extra RAM, the performance boost from the extra RAM will be far, far more than any marginal hit on bandwidth.

 

[weaverra]

It's the same obsession that has been with dual channel PC setups for over 15 years (the Rambus/DDR SDRAM wars). When you use all your available ram up you can notice the difference particularly with DDR3; far more than say smaller increases in the past like with DDR2 with smaller gaps such as 533,667,800. It's not much, probably 5 %. But marginal gains I do like. These Xeons come with a triple config - other CPU designs have a quad option.

My 4,1 came with 3x1Gb which is useless - so along with the hex Xeon I bought 3x8gb DDR 1333. Which means if I go dual socket I will have the same memory config for both processors for 48Gb.

I would think 16GB to be the minimum. It doesn't take much to fill that. You could probably make the argument once you have more than 16GB of ram going with the triple channel setup might be truly beneficial. 12GB doesn't seem like enough to really get the performance you need out of a triple channel configuration. I know with the usage I have had so far with my 16GB I haven't paged once whereas with 12 GB I would have most certainly by now.

 

[Gav Mack]

I would think 16GB to be the minimum. It doesn't take much to fill that. You could probably make the argument once you have more than 16GB of ram going with the triple channel setup might be truly beneficial. 12GB doesn't seem like enough to really get the performance you need out of a triple channel configuration. I know with the usage I have had so far with my 16GB I haven't paged once whereas with 12 GB I would have most certainly by now.

If it came with 3x4 for 12 and you needed that bit extra then another 4gb with a slight hit on bus speed is very sensible. I came from a maxed out 3,1 with 32gb and with the useless memory config I had, would like to have with dual socket, plus the fact that even with used ram that 3x16 is three times the cost of 3x8 made 24gb the most sensible option for my usage.

 

[ilikewhey]

nothing to do with obsession, more have to do with x58 is a triple channel setup, therefore it will three sticks of ram better than dual or quad.

 

[AidenShaw]

nothing to do with obsession, more have to do with x58 is a triple channel setup, therefore it will three sticks of ram better than dual or quad.

But so slightly better you probably won't be able to measure the difference.

On the other hand, 16 GiB of RAM may give an easily measurable improvement over 12 GiB.